BAGHDAD, Iraq (CNN) -- Nearly 600 more Christian families have fled the northern Iraqi city of Mosul over the past week, amid threats by Muslim extremists to convert to Islam or risk death, an official in Nineveh province said Monday.

An Iraqi policeman patrols outside a church in the Baghdad district of Dora last Tuesday.

Last week, Iraq's Ministry of Immigration and Displaced Persons said 1,424 Christian families had fled Mosul. Nineveh Deputy Gov. Khasro Goran said the number has since risen to 2,000, based on the most recent figures from Nineveh's office of Immigration and Displaced Persons.

Fourteen Christians have been slain in recent weeks in Mosul, which is about 260 miles north of Baghdad. On Friday, Iraqi security forces arrested four men in Mosul in connection with anti-Christian attacks.

Iraqi authorities believe al Qaeda in Iraq is behind the violence. Mosul is one of the last Iraqi cities where al Qaeda in Iraq has a significant presence and routinely carries out attacks.

Iraqi security forces continue to patrol the city daily -- particularly the city's Christian neighborhoods -- and violence has decreased as a result, Goran said. Despite this, more families have fled and very few families have returned, he said.

Authorities said the attacks may have been prompted by Christian demonstrations ahead of provincial elections earlier this month.

Hundreds of Christians took to the streets in Mosul and surrounding villages and towns, demanding adequate representation on provincial councils, whose members will be chosen in the local elections.

Iraqi leaders have expressed concern about the anti-Christian attacks.